Reservoir pen



ug. 12, 1952 E. v. WAGNER RESERVOIR PEN Filed July 12, 1 950 .fllllllllllllllllllflfl flllllllln .Hill Ufff. nl. rlllflllll lill, IA

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Patented Aug. 12, 1952 Urn'rro l p aEsEavoIaPEN i Ernest Verrnder'Wagner, London, England Application July `l2, 1950, Serial No. 173,280

In Great Britain July 1,8, 1949 4 Claims. 1

This invention relates to reservoir pens of the kind in which ink is abstracted, by writing with the writing tip, from a tubular ink reservoir without admission of air at the writing tip.

The object of the invention is to enable such a reservoir pen to be used with a tubular ink reservoir which has the end remote from the writing tip open to theatmosphere, by providing means to'restrainthe ink from leaking at such remote end. i

The invention consists of a tubular ink `reservoir for a reservoir pen o'f: the kind'set forth', in which reservoir there is a .waisted plug so constructed that it has peripheries at opposite ends of the waist of substantially the same diameter such that the plug slidingly lits within the reser- Voir, the plug being so disposed that one end only is in rcontact with `the ink surface remote from the writing tip, the periphery at the other end having a liquid applied thereto so as to trap air in the waist of the plug.

The expression waisted plug includes a plug having a single waist or a plurality of waists.

The expression liquid is meant to include such semi-liquids as for instance thick oils.

The plug'should not have such a specific gravity that there would be a risk that the plug would penetrate completely into the ink when the Writing tip is held downwards for a long time, and

preferably is such that its specific gravity does not substantially exceed that of the ink..

Provided that the plug has a suitable specic gravity, thenthe trapped volume of air will restrain the plug from penetrating entirely into the ink as long as the liquid meniscus at the periphery beyond the waist and remote from the ink remains unbroken.

This restraining effect can be increased by increasing the number of waists of the plug with a corresponding increase in the number of liquid meniscuses, each of which confines a further trapped volume of air, and all of which would have to be broken through by the trapped air before the plug could penetrate completely into the ink, i. e. before the ink could leak past the plug.

The accompanying drawings show, by way of example, embodiments of the invention, and in which:

Fig. l is a longitudinal section of a ball-tipped reservoir pen, and i Fig. 2 is an end elevati-on of the ink reservoir thereof.

Fig. 3 is a side elevation, partly in section, of a reservoir pen showing a plug having a plurality of waists.

Figs. 4 and 5 are longitudinal sections lof two further forms of waisted plugs.

Referring more particularly to Fig. 1, a is the casing or barrel of a reservoir pen partially closed at one end by a plug bwhich has an axial bore c in communication with the atmosphere.

d is the tubular ink reservoir of the pen and as shown consists of a drawn aluminium tube.

The hollow writing tipe of the pen is of metal, and is tightly tted in one end of the ink reservoir tube d.

fis the ball held in a seating in the outer end of the writing tip e whereby on writing with the pen the ink g is abstracted from the tip c and hence from the reservoir tube d.

The Writing tip e is frictionally held in the barrel a and is withdrawable together'with the ink reservoir tube d.

The end of the ink reservoir d remote from the writing tip e is open to the atmosphere.

The ink reservoir tube d can be of a larger bore than .has heretofore been thought practical with pens of this type, in which the usual bore has been about 0.1 inch (or about 2.5 mm.) and the supposed maximum about 0.14 inch (or about 3.5 mm). In the embodiment described the bore is 01.116 inch with a tolerance from -0 to +0.0005 inc To prevent the ink g leaking from the end of the ink reservoir tube ld remote from the writing tip e, a waisted plug h is freely slidingly provided in the tube d. The plug may conveniently be in. long, the lengths of each of the peripheries of the wide portions h1 and h2 may be 1/8 in. and the diameters of the wide portions h1 Aand h2 may be 0.157 inch with a tolerance from l-i-O to 0.001 inch. The face of h1 nearest to the ink is in contact with the ink g, and the periphery of the other wide portion h2 is wetted with oil such as castor oil. Such oil forms a meniscus which seals the clearance between the periphery of the plug portion h2 and the wall of the tube d. A volume of air is thus confined at the waist between the two portions h1, h2 of the waisted plug h.

It is believed that ink tends to interpose itself by capillary attraction along the narrow annular clearance between the plug portion h1 and the Wall of the tube d, and draw the plug portion h1 into the ink until restrained by the ensuing compression of the volume of air confined at the waist of the plug h. This restraining effect can be increased by increasing the number of waists of the plug h, Fig. 3 showing a plug h with three waists and three 'lha. h4. o1 wetted w1de portions h2,

To prevent the Waisted plug h being displaced into the ink g by misuse as for instance by someone inserting a wire into the end of the tube d, the end of the tube d remote from the Writing tip is preferably closed by pinching in mutually perpendicular directions as shown in Figs. 1 and 2. In such case a vent hole i is formed near the pinched end of the tube d to ensure that the plug h and the ink g is exposed to atmospheric pressure.

The waisted plug instead of being composed of aluminum, may be composed of a lighter solid material more nearly of the same specific gravity as the ink, but which must be a substance not aected by the ink.

Alternatively, the plug h can be rendered more buoyant in the ink g by providing a recess 7 in the ink-contacting end of h1 as shown in Figs. 4 and 5, so that a volume of air is trapped therein When the plug is in contact with the ink.

In Fig. 5, h1 is shouldered and as shown in this gure, there are three portions h1, h2 and h3 the peripheries of which are each of small axial length. Conveniently the plug shown in Fig. 5

may have a length of seven-sixteenths inches and l the length of the peripheries of h1, h2, h3 may each be si; in. which will minimise friction resisting the movement of the plug.

The peripheries h2, h3, h4 can either be wetted with oil before the plug is inserted in the ink i reservoir tube d, or the plug h can be inserted therein dry and a drop of oil subsequently dropped therein.

1. For a reservoir pen of the kind in which ink is abstracted by writing with a Writing tip without admission of air at the Writing tip, a tubular ink reservoir open at one end to the atmosphere, a Writing tip atV and closing the other end of said tubular reservoir, a waisted plug providing a space at said Waist of greater than capillary dimensions having peripheries at opposite ends of the Waist slidingly tting said tubular reservoir with one of said peripheries in contact with the meniscus of the ink in said tubular reservoir, and oil coating the other periphery and forming a ineniscus separate from said ink meniscus and trapping air at said Waist.

2. For a reservoir pen of the kind in which ink isabstracted by writing with a writing tip without admission of air at the Writing tip, a tubular ink reservoir open at one end to the atmosphere, a Writing tip at and closing the other end of said tubular reservoir, a plurally waisted plug providing a space at each of said Waists of greater than capillary dimensions having peripheries at opposite ends of the Waists sldingly fitting said tubular reservoir with one of said peripheries in contact with the meniscus of the ink in said tubular reservoir, and oil coating the other peripheries and forming meniscuses separate from said ink meniscus and trapping air at said Waists.

3. Means for preventing leakage of ink from an end open to the atmosphere of a tubular ink reservoir of a reservoir pen of the kind in which ink is abstracted by Writing with a Writing tip Without admission of air at the Writing tip, consisting of a Waisted plug providing a space at said Waist of greater than capillary dimensions adapted to slidably t said reservoir with one end in contact with the ink in said reservoir, and oil surrounding said plug at the portion of said plug more remote from ink in the reservoir than said waist and forming a meniscus extending from the plug` to the inner surface of said reservoir and trapping air at said Waist.

4. Means for preventing leakage of ink from an end open to the atmosphere of a tubular ink reservoir of a reservoir pen of the kind in which ink is abstracted by Writing with a Writing tip without admission of air at the writing tip, consisting of a plurally waisted plug providing a space at each of said Waists of greater than capillary dimensions adapted to slidably nt said reservoir with one end in contact with the ink in said reservoir, and oil surrounding said plug at the portions of said plug more remote from ink in the reservoil` than each of said Waists and forming meniscuses extending from the plug to the inner surface of said reservoir and trapping air at said waists.

ERNEST VERRINDER WAGNER.

REFERENCES CITED The following references are of record in the file of this patent: v

UNITED STATES PATENTS Number Name Date 68,727 Gabriel Sept. 10, 1867 960,413 Sanford June 7, 1910 2,249,163 Nissen, Jr July 15, 1941 2,426,453 Huenergardt Aug. 26, 1947 2,438,786 Moore Mar. 30, 1948 2,505,211 Schiesel Apr. 25, 1950 2,557,409 Brinson June 19, 1951 FOREIGN PATENTS Number Country Date 213,442 Switzerland May 1, 1941 

